Meeting Abstract
Intertidal fishes experience greater physical forces from currents and waves than subtidal fishes. In addition, some intertidal fishes may move over land from one pool to another; walking on land will increase the load that the fins will bear due to the forces of gravity. We hypothesized that intertidal sculpins (superfamily Cottoidea) have more ossification in their pectoral girdles and fins, relative to subtidal species. Using µCT whole-body scans of 35 sculpin species and calibration phantoms (hydroxyapatite-based objects of known density), we measured mineralization of the radials, cleithrum, and individual pectoral fin rays. From these analyses we have ascertained that benthic sculpins have asymmetrically ossified hemitrichia (paired halves of fin rays): the medial hemitrich is more ossified than the lateral hemitrich. This may be an adaptation to strengthen the region of the pectoral fin that typically is in contact with the substrate. In addition, intertidal and shallow-water sculpins have more heavily ossified pectoral girdles than do deep-water subtidal sculpins. In fact, ossification decreases linearly with habitat depth (R = -0.522) and the absolute number of pectoral fin rays also increases with habitat depth (R = 0.518). We suggest that the heavily ossified pectoral bones of intertidal and shallow-water sculpins may provide a safety factor that protects them them from the greater forces they experience in the wave-swept near-shore environment and on land.
